Using Classic Outlook on Windows for personal email, calendar, and contact management
Hello Alfie, Good day. Thanks for posting in the Microsoft Community.Apologies for the inconvenience caused to you by this behavior.May I know if your account is a personal account or a business account?If it is a business account, do you have another authentication method or sign in another way when it requires code?
If no, please confirm if you have another global administrator in your tenant. If you do, please use the other admin account to reset your authenticator.If you are the only global administrator, then you need to involve MS data protection team.To further resolve this, Microsoft’s data protection support team will need to step in. A technical support engineer can help you to resolve the problem. If the issue requires further attention, they can escalate it to a specialized team for deeper analysis.As forum moderators, we don’t have access to the backend systems to troubleshoot this effectively due to privacy and security constraints. For that reason, the most efficient solution would be to contact Microsoft’s support team directly.If you cannot login to admin center to raise a ticket, please follow the article to find the related hotline number to call the frontline let them raise a ticket for you: Customer service phone numbers - Microsoft Support
Best regards,
Trish - MSFT | Microsoft Community Support Specialist